I'm getting up to speed in ModelBuilder for Pro and I ran into an annoyance. I had a feature class that needed to be appended into another feature class but the field names are not the same. I added the field mappings and out of habit I click Validate Model after clearing intermediate data. I believe the validate function is wiping out the field mappings. If I avoid validating the model my manually matched fields stay matched, otherwise they are gone. It took me a minute to catch why my data wasn't appending correctly. Hopefully, this helps someone else. Feels like a bug, but there could be something in the validation logic invalidating the manually matched fields because they are, cough, invalid? ...name != name ?
